An aqueous dispersed resin composition comprising a carbonyl-containing copolymer resin aqueous dispersion and a hydrazine derivative containing at least two hydrazino groups in the molecule thereof is known (see, e.g., JP-A-57-3850, JP-A-64-48801 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), U.S. Pat. Nos. 4,267,091, 4,210,565, 5,208,282 and 4,959,428 and JP-B-1-13501 (the term "JP-B" as used herein means an "examined published Japanese patent application"). This composition easily undergoes crosslinking at room temperature to provide a film having various excellent physical properties. However, it rapidly dries after application, tending to suffer from unevenness of coating or cracks due to shrinkage stress.
In order to overcome these disadvantages, use of a large quantity of an emulsifying agent or addition of a wetting agent or a water-soluble resin has been attempted, but either attempt results in reduction in water resistance of a film to an impractical level.
In order to improve water resistance, external addition of an epoxy-containing compound or use of an epoxy-containing monomer as one of monomers constituting an aqueous resin dispersion has been proposed. The aqueous resin dispersions of this type exhibit improved water resistance but are apt to undergo gelation on account of the epoxy group. Therefore, the composition must be supplied as a two-pack type of formulation, which is troublesome to handle.